Work expulsion mechanism for furnaces



June 12, 1951 H. A. STRICKLAND, JR

WORK EXPULSIQN MECHANISM FOR FURNACES Original Fil'ed March 21, 1941 3 Sheets-Sheet 2 INVENTOR Harold Astricklcmdflr.

ATTORNEY Patented June 12, 1951 WORK EXPULSION MECHANISM FOR FURNACES Harold A. Strickland, Jr., Detroit, Mich., assignor, by mesne assignments, to The Ohio Crankshaft Company, Cleveland, Ohio, a corporation of Ohio Original application March 21, 1941, Serial No.

384,503, now Patent No. 2,408,350, dated September 24, 1946. Divided and this application January 10, 1946, Serial No. 640,228

6 Claims; (Cl. 219-47) This invention relates to furnaces for heating by electromagnetic induction, and particularly to such furnaces as are used or intended for use in the heating of bar or billet stock for forging purposes. This application is a division of my copending application Serial No. 384,503, filed March 21, 1941, entitled Electric Furnace Machine, now Patent No. 2,408,350, dated September 24, 1946.

In the application above referred to there is disclosed a furnace construction including a heat-- chamber and means generally referred to as push-out mechanism for removing the workpiece after the heating cycle has been completed in the furnace. This push-out mechanism includes a rod operable from the rear side of the furnace and having a contacting tip engageable with the rear end of the workpiece so that when the mechanism is energized the rod moves axially to push out the workpiece to a point where it can be grasped by tongs or the like for complete removal.

A primary object of the present invention is to provide mechanical, readily actuated means for moving a furnace workpiece to a point where it is accessible to the attendant. Another object of the invention is to provide push-out mechanism which may be adjusted to workpieces of different linear length.

I furnace flux at the end of the heating chamber.

Other objects will appear on consideration of the specific structure hereinafter described.

Referring to the figures:

Figure 1 is a side elevation of a furnace to which my invention is applicable, with parts broken away to show the operating mechanism for the push-out rod;

Figure 2 is a side elevation in section of the furnace coil and associated'parts, with enlarged detail of the push-out mechanism;

Figure 3 is a detailed View showing the rear end of the push-out rod and operating parts;

Figure 4 is a side view of the mechanism as shown in Figure 3; and

Figure 5 is a detail illustrating the pedal device used for operating the push-outmeans.

' In Figure 1 of the drawings there is illustrated a furnace in side elevation to which my inv'n tion is applicable. On the base In an L -shaped 2 structure 30 constituting the furnace as a whole is mounted, this furnace having an L-shaped section with a horizontal branch 3! and a vertical branch :23 forming an angular recess in which the furnace proper is placed. This furnace is designated by the numeral 40 applied to the in duction coil and the numeral 41 applied to the casing which completely encloses the coil and associated appurtenances. In the L-shaped structure 3i-33 are mounted the operating mechanism for a push-out rod assembly 58 and in the casing l? are included the induction coil unit 40, the C-brackets 98 with their supporting bases 9?", a flux drum 0?, and a section of the push-out rod extending from the section 33 of the L-unit. The casing M is provided at the front end thereof opposite to the casing section 33 with a door open,- ing for insertion of a workpiece, the hinged door 52 overlying this opening to protect it from flame blast gases in removal of the workpiece prior to completion of the heat treatment.

In Figure 2 is given greater detail of the fur,- nace construction wherein it is seen that the coil unit 46 is comprised of an outer insulating cas ing 59 of any suitable material overlying the furnace coil which is in tubular form. The Work? piece chamber, in which a workpiece H is indicated, is spaced from the coil by fire brick l i and a framework of tubular guides 16 embedded in the fire brick on which internally thereof are mounted retaining lugs 19 and load bearing lugs At the inlet opening of the front casing 5%! a casting at is placed having a central opening 580 and inwardly directed guide fingers I which bend inwardly at their tips to form a con stricted opening adjacent the open outer end of the furnace chamber of the coil unit 40. By this the workpiece is guided into the furnace chamber on to the bearing lugs 88 of the guide tubes and is consequently positioned for heat treatment. When so positioned and the door 522 closed the heating cycle is commenced which brings the workpiece to the desired temperature. The heat is then automatically turned off and the door 52 opened, at which time the workpiece may be removed. The mechanism for accomplishing the removal is incorporated in the push out mechanism 58 comprising a push-out rod I40 movable in a supporting tube 143, which tube is frequently referred to as a stock-gauge.

The push-out mechanism 58, and the flux drum or magnetic core 81 of the coil 40 associated therewith, all coact with the axially inner end of the workpiece at or near the axially inner end of the coil 40. While they arelocated workpiece.

generally in Figures 1 and 2, their detail is depicted generally in Figures 3, 4 and 5. Referring particularly to Figures 2 and 4 for the moment, it will be seen that the stock-gauge per se' comprises a tubular member I43 lying on the axis of the coil 46, and supported from the plate 42 of the coil casing for relative axial adjustment by a clamping bracket I44 bolted to the plate 42. The tubular member I43 projects rearwardly through the plate 42 a considerable distance allowing it to be axially adjusted back and forth through the clamp I44, to adjust its forward end with respect to the axially inner end of the coil 46, thereby to engage an inserted workpiece in different axial positions within the coil 46. Once adjusted for the proper gauging of the stock, for the proper heating thereof through the proper length, the gauge member I43 may be firmly clamped in its supported position.

The flux drum or magnetic core is mounted on this adjustable member I43, shown in Figure 2 as being fixed although it may be adjustable. The magnetic core 91 is comprised of an annular series of radially extending, radially tapering laminations, the details of which are no part of the present invention and are, therefore, not shown. Sufficeth to say, they are bound in place upon the support I43 or equivalent support by any suitable means such, for example, as the commonly known interlocking tongue and groove device I45. This magnetic core is of considerable diameter and axial extent. Therefore, a considerable magnetic mass is shown as of approximately the diameter of the workpiece accommodatable by coil 46. As projected in juxtaposition to the end of a workpiece, it receives the fiux flowing external to the coil 46, collects and concentrates it, and conducts it more or less directly axially inwardly of the inner end of the Its utilization and relative adjustment with respect to the end of the workpiece very considerably improves the reluctance of the magnetic circuit and affords a very flexible control of the distribution of heat in the heating of the axially inner ends of the workpiece. Thus with the proper gauge of the stock in position within the coil 46, plus adjustment of the flux through its axially inner end, irr gular or imperfect heating or excessive heating in any portion in the inner end of the bar may be avoided. Thus it combines with such portion of the stock as may project from the outer end of the furnace to achieve a general reduction in the reluctance of the circuit.

The push-out mechanism comprises a preferably though not necessarily water-cooled pushout rod I46 working axially back and forth within the tubular support I43. The engaging tip I41 of the push-out rod I46 is made of heatresisting metal or other such material, and is preferably removably secured to the end in a manner not shown, but well known in connection with welding electrode tips and the like.

This push-out or ejector rod M6 is axially projectable through the tubular support I43 by means of the long arm I54- of a bell crank pivoted at I55 and whose short arm I56 is connected with piston I51 of a floating fluid pressure cylinder I58 linked at I59 to a bracket i655 secured to the rear face of plate 42. The spring l2 moves the arm I 55 against the action of the piston and cylinder. Bell crank I54, I56 is itself supported along with other parts of the mechanism from a larger bracket i6I also secured to the plate 42. Engagement of arm I54 with the ejector rod I46 is a one-way engagement toward the coil through contact of its forwardly bent upper end I62 with an adjustable collar I63 about the rod, whereby the length of the rod may be made sufiiciently great to enable it to be used in connection with workpiece stock of various lengths as associated with coils 46 of various lengths, the relation between the tip I41 and the collar I63 being appropriately adjusted to the ejection requirements of stock and coil sizes and positions and stroke of the push-out mechanism at large.

The stroke of the push-out mechanism is achieved by fluid pressure applied through conduit 60 from a master cylinder 59 of the automobile brake type operated by foot pedal I64. The system is kept filled from the usual reservoir I65 as in the automobile practice. The stroke of cylinder 59 and hence of the ejector rod I46 is regulatable by an adjustment of the leverages through which foot pedal I64 is connected to the piston rod of cylinder to. Pedal a bellcrank whose short arm 36, to which retracting spring I61 is connected, is adjustably fulcrumed at I68 upon a fulcrumed bearing bracket l69. Bracket I69, together with pedal I64 and cylinder 59 and appurtenant parts, are all borne from a removable mounting plate I16 bolted to the face of the housing section 3I, whereby the ensemble of this foot-pedal--operated actuating mechanism is removable as a unit from the housing 3I through the opening I'II, without disconnecting from hose 66, and to the extent permitted by the provided length of flexible hose 66, merely by disconnecting the plate E16. A heel 12 on lever I64 abuts the inner face of the mounting plate I16 at the outer extreme of the stroke. Further stroke adjustment can had through the screw-threaded adjustment of piston rod I65 with respect to link H3 means of which it is connected to pedal I Workpiece stock-limiting switch I14 (see Figures 3 and 4) is also operated in connection with the push-out rod I46. This is achieved through the long arm of bell-crank lever I15, I 16, which long arm through a forwardly projected end I11 also has a one-way forward engagement with the adjustable collar I63. Like the bellcrank I54, I56, the bell-crank I15, I16 is freely journalled on the pivotal shaft I55. Unlike the bell-crank I54, I56, the arms of which are integral, the bell-crank I15, I16 has its arms relatively adjustable, the short arm I16 being adjustably clamped by a split collar I18 surrounding a lateral extension I16 of the hub of the long arm I15. Arm I16 forms a segment about the axis I55, and on an outer arc-shaped periphery I86 of this segment rides the switch-actuating roller arm I8l of the limit switch I14. Bellcrank I15, I 16 is biased toward a forward position by a spring I82 extending to back plate 42, and the roller of roller arm IBI, when the bell-crank is in its extreme forward position and the workpiece has been pushed out, engages in an arcshaped depression 583 in this segment. By angularly relatively adjusting the arm I16 with respect to arm I15, the action of limit switch I14 may be adjusted effectively for each adjustment of collar !63. Switch I14 is mounted upon a bracket !84 also borne by back plate 42. The switch I14 may be connected to suitable control circuits such that when the switch is actuated, energization of the heating coil of the induction coil unit 46 may take place. The particular circuits other than the initiation function of the (6 switch I14 form no part of the present invention and will not be described or shown in detail. A preferred embodiment of a circuit into which the switch I74 may be connected is shown in Figure 19 of the parent application referred to above out of which this application has been divided.

Thereupon the heated workpiece may be removed simply by pushing downwardly on foot pedal I64. This actuates cylinder I 58 to rock crank I54 about its axis I55 to engage the upper end of the crank with collar I63 on push-out rod I46, therethrough to push the workpiece axially outwardly. Simultaneously, it may be grasped in suitable tongs and removed for placement in the forging machine or other instrumentality used to treat or form it.

As is clearly described in the above referred to patent, upon removal of the workpiece the load switch I74 is opened, thereby opening the operating circuits of the furnace. In the event that the workpiece is not removed after the heating cycle, the circuits and switch mechanism are maintained in open position so that the power may not be reapplied to the same load as long as it remains in the furnace. This is simply because as long as a workpiece is in the machine, the push-out rod I 46 through collar I63 retains rock arm I15 in its rearward position against the tension of spring I82, in which cam I80 retains switch arm IBI raised and switch I74 closed. Thus an operator is compelled to notice that a workpiece has been partially heated and refrains from replacing it in the machine until after it has been cooled. Overheating of a workpiece through subjection to one whole heating cycle and after exposure to a fraction of a prior heating cycle is thus prevented.

The mechanism as above described is direct in its actuation and may be manipulated readily by the operator to bring about movement of the workpiece to a point where it may be easily removed from the furnace chamber.

Modifications of the precise operating mechanism obviously may be made within the scope of the appended claims.

What is claimed is:

1. An apparatus for heating a workpiece by electromagnetic induction comprising an induc tion heating coil, a track for supporting the workpiece during heating, a laminated magnetic core adjacent the end of a workpiece when in heating position and in general prolongation of the workpiece, a stock gauge by which the core is supported, said stock gauge extending through the core, and a workpiece push-out device slidable through said core and guided within and by said stock gauge.

2. A machine for heating workpieces comprising in combination, a tubular heating coil having at least one end open for the insertion and removal of a workpiece and workpiece removing mechanism positioned adjacent the other end of the coil for moving the workpiece toward the open end, said mechanism including a rear index stop for the workpiece, said stop being adjustably supported to fixed positions along the axis of said coil.

3. A machine for heating workpieces comprising in combination, a tubular heating chamber having at least one end open for the insertion and removal of a workpiece, an indexing stop for the workpiece adjacent the other end of the chamber, said stop comprising an adjustably mounted tube and a plunger rod in said tube for pushing the workpiece toward the open end..

4. A machine for heating workpieces comprising in combination, a tubular heating chamber having at least one end open for the insertion and removal of a workpiece, an indexing stop for the workpiece adjacent the other end of the chamber, said stop comprising an adjustably mounted tube and a movable plunger rod in said tube for moving the workpiece towards the open end, said plunger also having adjustable stops to vary its stroke and its action on the workpiece.

5. A machine for heating workpieces, comprising in combination, a frame, means on said frame for supporting tubular heating coils of different length, an induction heating coil supported on said supporting means, an adjustably supported magnetic core positioned at one end of the coil so as to be adjustable to new positions to accommodate different lengths of coils, a tubular support for said core adjustabl mounted so as to provide a variable index stop for a workpiece in said coil, a workpiece push-out plunger operably mounted in said tubular support and having an adjustable stroke to push a workpiece a determinable amount toward an open charging end of said coil, mechanism for positively actuating said plunger in the push-out direction, the plunger being returned by the insertion of a workpiece, and a control switch for energizing said heating coil operated by said plunger on its return movement by the workpiece.

6. In induction heating apparatus including an electric induction heating coil having a passage in which workpieces are adapted to be positioned for the purposes of heating same, the improvement which comprises: means for moving workpieces toward one end of said coil for removal from said passage, said means including a member positioned generally at the end of said coil remote from said removal end and movable in the direction of said removal end, said member having a portion adapted to engage a workpiece, movement of said member in said direction pushing a workpiece along a path extending through the passage of the coil and elements operatively associated with said member for controlling movement of said member in the opposite direction for controlling the position of a workpiece in said passage as a workpiece is inserted.

HAROLD A. STRICKLAND, JR.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 716,680 Daniels et a1. Dec. 23, 1902 756,946 Edwards Apr. 12, 1904 1,516,970 Kiger Nov. 25, 1924 1,646,498 Seede Oct. 25, 1927 1,749,700 Fourment Mar. 4, 1930 1,815,666 Cook et al July 21, 1931 1,838,015 Forster et al Dec. 22, 1931 1,870,619 Flanzer Aug. 9, 1932 1,980,875 Northrup Nov. 13, 1934 1,981,631 Northrup NOV. 20, 1934 1,989,376 Northrup Jan. 29, 1935 2,108,355 Swift Feb. 15, 1938 2,277,564 Somes Mar. 24, 1942 2,379,463 Strickland July 3, 1945 2,402,852 Strickland July 25, 1946 

